Pump or motor



W. FERRIS Jan. 11, 1938.

PUMP OR MOTOR Filed Dec. 13, 1935 3 Sheets-Sheet l N YQ o //V @/,N g M w M n iv .3 m In .5 MW Mm .n WW q 9 m .0 a m o I l l I I I Q i? !NVEN'TOR\ 'f" \NIALTER Teams BY I Jan. 11, 1938.

W. FERRIS PUMP OR MOTOR Filed Dec. 13, 1955 5 Sheets-Sheet 2 INVENTQR VVALTER FEHHIS :TTORNEY Patented Jan. 11, 1938 warren stares PUMP OR MOTOR Walter Ferris, Milwaukee, Wis, assignor to The Oilgear Company, Milwaukee, Wis, a corporation of Wisconsin Application December 13, 1935, Serial No. 54,189

8 Claims.

This invention relates to pumps or motors of the type in which the cylinders are arranged in a rotatable cylinder barrel, a piston-is fitted in each cylinder and provided at its outer end with 5 a contact face which is inclined to the piston axis, and a thrust member engages the contact face on each piston at one side of the piston axis and is so arranged that it forces each piston inward during one part of the revolution of the cylinder barrel and permits it to move outward during another part of the revolution of the cylinder barrel whereby, during reciprocation of the pistons, relative movement between each piston and the thrust member causes the contact face on the piston to roll upon the thrust member and the piston to rotate within its cylinder, such as the pump described and claimed in Patent No. 2,074,068 which issued March 16, 1937 on application Serial No. 662,219, filed March 23, 1933 of on which this application is a continuation as to matters common to both applications.

A machine of the above type will function as a pump when it is driven mechanically and will function as a motor when driving liquid is sup 23 plied to its cylinders. For the purpose of illustration, the machine will be referred to herein as a pump and the invention will be explained as a pump but it is to be understood that the invention is equally applicable to a motor of the same 3:) type.

The present invention has as an object to provide a rolling piston pump which is very compact.

Another object is to provide a rolling piston pump which is more economical to manufacture 35 than the previous rolling piston pumps.

Other objects and advantages will appear from the description hereinafter given of a pump in which the invention is embodied.

According to the invention in its general aspect 40 and as ordinarily embodied in practice, the pump has its pistons and cylinders arranged in a rotatable cylinder barrel and inclinedto the axis thereof, a thrust ring is arranged around the cylinder barrel eccentric thereto and engages the 45 outer end of each piston at a. point offset from the piston axis whereby during rotation of the cylinder barrel the pistons will be simultaneously reciprocated and. rotated.

The invention is exemplified by the pump illus- 50 trated in the accompanying drawings in which the views are as follows:

Fig. 1 is a central longitudinal section through the pump as indicated by the line l| of Fig. 2.

Fig. 2 is a transverse section taken on the 55 line 2-2 of Fig. 1.

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 1. r

Fig. 4 is a force diagram.

'Fig. 5 is a central longitudinal section through a Dump having two circular rows of pistons. 0

Figs. 1 to 4 The pump has its mechanism arranged within and carried by a casing l which is provided at its rear end with an integral hub or boss 2 of substantial thickness and at its front end with a removable head 3.

Theboss 2 has a valve shaft or pintle 4 secured therein at its rear end in axial alinement with a drive shaft 5 which is journaled in the front head 3 in a suitable bearing and restrained thereby from axial movement.

The pintle 4 extends into the casing I and has two segmental ports 6 and 1 formed therein diametrically opposite each other near the front end thereof. The ports 6 and I communicate, respectively, with an upper passage 8 and a lower passage 9 which extend longitudinally of the pintle and communicate, respectively, with a passage IO and a passage I l which are formed in the boss 2. The pump may be connected into a hydraulic circuit by means of two pipes I2 and I3 which are attached to the boss 2 and communicate, respectively, with passages l0 and II.

The pintle 4 has closely fitted upon the front part thereof a rotatable cylinder barrel l4 which has a plurality of cylinders i5 formed therein in.

a circular row. Each cylinder I5 is inclined to the cylinder barrel axis and provided at its inner end with a port It which communicates with the pintle ports 6 and 'l alternately as the cylinder barrel rotates.

When the pump is in operation, a small volume of liquid from the cylinders is forced between the bearing surfaces of the cylinder barrel and the 40 pintle and forms a lubricating film upon which the cylinder barrel rotates. This film is subjected to pump pressure and tends to move the cylinder barrel toward the high pressure or discharge side of the pump and thereby cause it to bear more heavily upon the low pressure or intake side of the pintle. In order to overcome this tendency, pressure limiting grooves H are formed in the pintle to determine the width of the region of high pressure tending to lift the cylinder barrel 5 away from the pintle on the high pressure side thereof. The area of this region is so proportioned that the fluid pressure acting upon the inner ends of the cylinders and tending to hold the cylinder barrel against the pintle is equal to or greater than the separating pressure of the film between the surfaces tending to lift the cylinder barrel away from the pintle.

The cylinder barrel is connected to the drive shaft through a flexible or universal joint in order that slight manufacturing errors or misalinement of parts may not prevent the cylinder barrel from floating freely upon the pintle. As shown, shaft 5 is provided at its inner end with an integral reduced portion 18 which is supported in an anti-friction bearing l9 inserted in the inner end of pintle 4 and carried thereby. A coupling 29 is splined upon shaft 5 and has an annular boss 2| formed on its inner face and arranged-within a recess 22 which is formed in the end of cylinder barrel l4. Recess 22 has a ring 23 arranged therein between its outer the outer peripheral wall and the outer periphery of boss 2| and spaced slightly therefrom.

-Rotation is transmitted from drive shaft 5 through two pins 24 to ring 23 and from ring 23 through two pins 25 to cylinder barrel l4. Pins 24 are arranged diametrically opposite each other and fitted in two holes each of which is formed partly in boss 2| and partly in ring 23. Each pin 25 is spaced 90 from the pins 24 and fitted in a hole which is formed partly in ring 23 and partly in cylinder barrel l4.

Each cylinder l5 has a piston 26 fitted therein and provided at its outer end with a contact face 21 to engage the inner face of a thrust ring 28 which extends around the cylinder barrel and is fixed in a rotatable drum 29 and rotated there'- with substantially in synchronism with the cylinder barrel by frictional rotative forces transmitted through the pistons. Thrust ring 28 is fixed indrum 29 in any suitable manner as by being closely fitted therein and restrained from axial movement by spacer rings. In actual practice, an ordinary ball bearing having a hardened inner race is often employed in small size pumps in place of thrust ring 28 and drum 29.

Drum 29 is arranged within a cradle 30 and provided at its front end with a tubular hub 3| and at its rear end with a tubular hub 32 which are fitted, respectively, in ball bearings 33 and 34 carried by the front and rear walls of cradle 30. Bearings 33 and 34 permit drum 29 to rotate but restrain it from axial movement. Shaft 5 and pintle 4 extend through hubs 3| and 32 respectively, and the inside diameter of each hub is great enough to permit drum 29 to be shifted transverse to the pintle axis to change pump displacement.

Cradle 30 is adjustable in a horizontal plane transverse to the pintle axis but is positively restrained from movement in any other direction. As shown, it is restrained from rearward movement by the rear wall of easing I, from forward movement by a plate 35 which forms the inner wall of front head 3, and from vertical movement by the upper and lower walls of easing I. In order to reduce frictionand wear. cradle 39 is provided with a plurality of slide plates 36 each of which engages shown in Fig. 2.

When the axis of thrust ring 28 coincides with the axis of cylinder barrel l4, the pump is at zero stroke and no liquid will be delivered thereby. When cradle 30 is shifted in one direction or the other from its central or neutral position, the

a bearing plate 31 as pump will deliver liquid in one direction or the other and at a rate depending upon the direction and distance the axis of thrust ring 28 is offset from the axis of cylinder barrel l4.

Cradle 39 may be shifted by either manual or power means according to common practice. As shown, it is adapted to be moved in one direction by a spring 38 and in the opposite direction by a piston 39 which is connected thereto by a rod 40 and fitted in a cylinder 4| formed in one side wall of easing I. Spring 38 engages cradle 30 at a point opposite rod 40 and reacts against the end wall of a recess 42 which is formed in the other side wall of easing I.

Spring 38 and piston 39 may be adapted to move cradle 3!! far enough to shift the axis of thrust ring 28 from one side of the cylinder barrel axis to the other side thereof to reverse the direction of pump delivery or stops may be provided to prevent cradle 30 from moving far enough to shift the axis of the thrust ring past the cylinder barrel axis so that the pump will deliver liquid in but one direction as long as the cylinder barrel rotates in the same direction. Also, either spring 38 or piston 39 may shift cradle 30 in a direction to increase pump displacement and the other shift it in a direction to decrease pump displacement.

As shown, piston 39 will shift cradle 30 from its neutralposition toward the right in respect to Fig. 2 to increase pump displacement when motive liquid is delivered to the head end of cylinder 4| as by means of a pipe 43, and thereafter spring 38 will shift cradle 30 toward its neutral position to decrease pump displacement when liquid is allowed to escape from the head end of cylinder 4|.

When cradle 39 has been shifted toward the right and cylinder barrel i4 is rotating in the direction of the arrow, the pistons in the lower half of cylinder barrel M will move progressively outward and draw liquid into their cylinders through passage .9 and port 1, and the pistons in the upper half of cylinder barrel I4 will be forced progressively inward and expel liquid from their cylinders through ports l6 and 6 into passage 8.

If cylinder barrel l4' should be rotated in the opposite direction or if the axis of thrust ring 28 should be shifted to the opposite side of the cylinder barrel axis, the direction of pumpdelivery wouldbe reversed but if both of these adjustments were made the direction of pump delivery would remain the same.

Liquid for actuating piston 39 may be supplied from any suitable source such as a gear pump which has its driving gear 44-fixed on drive shaft, 5 and its driven gear 45 journaled upon a stub shaft 45 fixed in front head 3, gears 44 and 45 being fitted in a suitable pump chamber 41 which is formed in front head 3 and closed by plate 35.

When the pump is in operation and thrust ring 28 is arranged eccentric to the cylinder barrel so that each piston is forced inward during one half-revolution of the cylinder barrel and is permitted to move outward during the other halfrevolution, the distance between the contact face 21 on each piston and the axis of the cylinder barrel changes twice during each revolution with a resultant variation in the linear speed of the outer end of each piston.

Since thrust ring'28 is rotated by contact with all of the pistons, it moves at substantially the half-revolution of the cylinder barrel and slower iii) than that point during the otherhalf-revolution.

If the thrust ring engaged the piston upon its axis and transmitted pumping forces to the piston parallel to the piston axis, the piston would slide upon the thrust-ring and create friction which would detract from the efficiency of the pump.

In the pump shown in Patent No. 2,074,068, sliding friction between the piston and the thrust ring is avoided by providing the thrust ring with an inclined inner face and providing each piston with an enlarged head having an arcuate contact face which is engaged by the inclined face on the thrust ring at a point ofi'set from the piston axis whereby, during reciprocation of the piston, the piston head rolls along the thrust ring and the piston rotates in the cylinder.

In order to simplify the piston construction and to make the pump more compact, pistons 26 are inclined to the radii of the. cylinder barrel and each is provided with an outer end or head which is substantially the same diameter as the body of the piston, and thrust ring 28 is provided with a cylindrical inner surface which engages the contact face 21 on each piston upon a single spot 48 (Fig. 4) which is offset far enoughfrom the piston axis to cause contact face 21 to roll along the inner surface of thrust ring 28 and the piston to rotate in its cylinder as the cylinder barrel rotates.

The contact face 21 on each piston is an arcuate but non-spherical generated surface the radii of which radiate from points outside the piston axis. It is ordinarily produced by beveling the outer end of the piston and then arranging the piston in a fixture corresponding to cylinder barrel I l and rotating the fixture with the outer end of the piston in contact with an abrading surface which corresponds to the inner surface of thrust ring 28.

Pumping force is transmitted from thrust ring 28 through spot 48 to piston 26 in a direction at right angles to the cylinder barrel axis as indicated by line fill-49 on Fig. 4. The liquid in the cylinder reacts upon the inner end of the piston and the resultant of this reaction lies along a line 5050 which intersects the line of pumping force at a point 5i which is intermediate the ends of the piston and well within the cylinder in all positions of the piston. The pumping force is thus resolved into two components one of which acts along line 50-50 and urges the piston inward and the other of which extends from point 5|, as indicated by arrow 52, and reacts upon the wail of the cylinder at right angles thereto so that the piston bears evenly upon the wall of the cylinder and no tilting of the piston or uneven wear will result. The forces acting upon the cylinder barrel are so nearly balanced that the cylinder barrel substantially floats upon the pintle and little if any force is required to restrain it from axial movement.

Fig. 5

The pump shown in this figure is substantially the same as the pump shown in Figs. ito 3 except responding parts previously described. Otherwise these parts remain unchanged.

Cylinder barrel It is provided with two rows of cylinders l5 which are inclined to the radii of the cylinder barrel and have pistons i6 fitted therein. The cylinders in one row are inclined in one direction and the cylinders in the other row are inclined in the opposite direction. Each cylinder is connected at its inner end to the adjacent cylinder in the opposite row by a cylinder port Iii which communicates with the pintle ports alternately as the cylinder barrel rotates.

The pistons 26 in each row have the contact faces 2'! thereof normally held in engagement with the inner face of a thrust ring 28 which is fixed in drum 2!! as by being closely fitted therein and spacedfrom the other ring 28 by a suitable spacer ring. The pump functions in the same manner as the pump previously described.

The invention herein described is susceptible of various modifications without'departing from the scope thereof as hereafter claimed.

The invention is hereby claimed as follows:

1. A pump, comprising a casing, a pintle fixed in said casing and having ports and passages formed therein, a cylinder barrel journaled upon and carried by said pintle and provided with cylinders which communicate with said pintle ports alternately as said cylinder barrel rotates, said cylinders being inclined to the radii of said cylinder barrel, means for rotating said cylinder barrel, a cylindrical piston fitted in each cylinder and provided with an arcuate contact face upon its outer end, and'a thrust ring arranged around said cylinder barrel and engaging said contact face upon a single spot which is at all times offset far enough from the piston axis to cause the piston to rotate in its cylinder during rotation of said cylinder barrel.

2. A pump, comprising a casing, a pintle fixed in said casing and having ports and passages formed therein, a cylinder barrel journaled upon and carried by said pintle and provided with cylinders which communicate with said pintle ports alternately as said cylinder barrel rotates, said cylinders being inclined to the radii of said cyl-.

inder barrel, means for rotating said cylinder barrel, a cylindrical piston fitted in each cylinder and provided with an arcuate contact face upon its outer end, a thrust ring arranged around said cylinder barrel and engaging said contact face upon a single spot which is at all times offset far enough from the piston axis to cause the piston to rotate in its cylinder duringrotation of said cylinder barrel, and means for rotatably supporting said thrust ring to permit it to be rotated in unison with said cylinder barrel by contact with said pistons.

3. A pump, comprising a casing, a pintle fixed in said casing and having ports and passages formed therein, a cylinder barrel journaled upon said pintle and provided with cylinders which communicate with said pintle ports alternately as said cylinder barrel rotates, means for rotating said cylinder barrel, a cylindrical piston fitted in each cylinder and provided with an arcuate contact face upon its outer end, and a thrust ring arranged around said cylinder barrel and having a cylindrical inner surface in engagement with 'the contact faces on said pistons, said cylinders and pistons being inclined to the radii of said cylinder barrel at such an angle that said thrust engages the contact face on each piston upon a single spot'which is offset far enough from the formed therein, a cylinder barrel journaled upon provided with cylinders which said pintle and said pintle ports alternately as communicate with 'said cylinder barrel rotates, means for rotating said cylinder barrel, a cylindrical piston fitted in each cylinder and provided with an arcuate contact face upon its outer end, a thrust ring ar-' ranged around said cylinder barrel and having a cylindrical inner surface in engagement with the contact faces on said pistons, said cylinders and pistons being inclined to the radii of said cylinder barrel at such an angle that said thrust ring engages the contact face on each piston upon a single spot which is offset far enough from the piston axis to cause the piston to rotate in its cylinder during rotation of said cylinder barrel, and means for rotatabiy supporting said thrust ring to permit it to be rotated in unison with said cylinder barrel by contact with said pistons.

5. A, pump, comprising a casing, a cradle arranged within said casing, a hollow drum supported within said cradle to rotate therein, a thrust ring fixed to the inside of said drum, a pintle having one end fixed to said casing and its other end extending into said drum and provided with intake and exhaust ports and passages, a cylinder barrel arranged Within said drum and journaled upon said pintle,-means for rotating said cylinder barrel, cylinders arranged in said cylinder barrel and provided with ports to communicate with said pintle ports alternately as said cylinder barrel rotates, and a cylindrical piston fitted in each cylinder and provided at its outer end with an arcuate contact face to engage the inner surface of said thrust ring, said pistons and cylinders being inclined to the radii of said cylinder barrel at such an angle that said thrust ring engages the contact face on each piston upon a single spot which is offset far enough from the piston axis to cause the piston to rotate in its cylinder during rotation of the cylinder barrel.

6. A pump, comprising a' casing, a cradle arranged within said casing, a hollow drum supported within said cradle to rotate therein, a thrust ring fixed to the inside of said drum, a pintle having one end fixed to said casing and its other end extending into said drum and provided with intake and exhaust ports and passages, a cylinder barrel arranged within said drum and journaled upon said pintle,'means for rotating said cylinder barrel, cylinders cylinder barrel and provided with ports to communicate with said pintle ports alternately as said cyinder barrel rotates, a cylindrical piston fitted in each cylinder and provided at its outer end with an arcuate contact face to engage the inner surface of said thrust ring, said pistons and cylinders being inclined to the radii of said cylinder barrel at such an angle that said thrust ring engages the contact face on each piston upon a single spot which is offset far enough from the piston axis to cause the piston to rotate in its cylinder during rotation of the cylinder barrel, and means for shifting said cradle transversely of said casing to thereby vary pump displacement.

'7. A pump, comprising a casing, a pintle fixed in said casing and having ports and passages formed therein, a cylinder barrel journaled upon said pintle, means for rotating said cylinder barrel, cylinders arranged in said cylinder barrel in a plurality of circular rows and provided with, ports to communicate with said pintle ports alternately as said cylinder barrel rotates, said cylinders being inclined to the radii of said cylinder barrel and the cylinders in different rows being inclined indifferent directions, a cylindrical piston fitted in each cylinder and provided with an arcuate contact face upon its outer end, and a thrust ring arranged around said cylinder barrel and engaging said contact face upon a single spot which is offset far enoughfrom the piston axis to cause the piston to rotate in its cylinder during rotation of said cylinder barrel.

8. A pump, comprising a casing, a pintle fixed in said casing and having ports and passages formed therein, a cylinder barrel journaled upon said pintle, means for rotating said cylinder barrel, cylinders arranged in said cylinder barrel in a plurality of circular rows and provided with ports to communicate with said pintle ports alternately as said cylinder barrel rotates, said cylinders being inclined to the radii of said cylinder barrel and the cylinders in different rows being inclined in different directions, a cylindrical pisv ton fitted in each cylinder and provided with an arcuate contact face upon its outer end, a thrust ring arranged around said cylinder barrel and engaging said contact face upon a single spot which is offset far enough from the piston axis to cause the piston to rotate in its cylinder during rotation of said cylinder barrel, and means for rotatably supporting said thrust ring to permit it to be rotated in unison with said cylinder barrel by contact with said pistons.

WALTER FERRIS.

arranged in said? 

